82128100 A00 217 2 CE Book 1 Aug68 pdf

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CONTROL DATA

CORPORATION

CONTROL

DATA®

217·2

EQUIPMENT CONTROLLER

This Publication Includes Information on the Listed Equ ipments:

FC710-A FC710-B FC711-A FC711-B

• General Description

• Operation and Programm i ng

• Installation and Checkout

• Theory of Operation

• Maintenance

• Maintenance Aids

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217-2

EQUIPMENT CONTROLLER

CUSTOMER ENGINEERING MANUAL

BOOKS IN THIS MANUAL:

Book 1 - - General Description

Operation and Programming Installation and Checkout Theory of Operati on Ma i ntenance

Maintenance Aids

Book 2 . - - Diagrams

Any comments concerni ng th is publication should be addressed to:

Publ ication No .. .82128100 April 1969

Contro I Data Corporation Data Display Division Technical Services Department

2401 North Fairview Avenue St. Paul, Minnesota 55113

e

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217-2 Equipment Controller

CUSTOMER ENGINEERING MANUAL - BOOK 1

REVISION RECORD

REVI S ION

DESCRIPTION

A-O-O Released

(8/68)

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. "

~~ll:t~.LI!&C':·A~'"

:ft\'/RSIISI~"

--

...

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DOl 219 REV 3/68

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82128100

217-2

Equi pment Controller

Customer Engi neeri ng Manual

Book 1

EQUIPMENT CONFIGURATION

The FCO and configuration levels for each equipment discussed in th is document are listed in Book 2 (pub-lication number 82128200) of th is manual.

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217

FOREWORD

The purpose of this manual is to provide a systematic approach to the funda-mental operating principles of the 217-2 Equipment Controller. This book (Book 1 of 2) covers two major areas: Theory of Operation (Section IV) and Maintenance (Section VI). Remain ing sections provide support information.

• Section I, General Description - acquaints the reader with the structure of the controller while providing physical, electrical, and e nv i ronmen ta I pa ramete rs •

• Section II, Operation and Programming - describes all switches, indi cators, and controls located on or with in controller cabinetry. Programming is generally on a systems basis. See the 200 User Terminal Reference Manual (publication number 82128000) for details.

• Section III, Installation and Checkout - lists the procedures required to make the controller operationa I from the in itia I uncrating state.

• Section IV, Theory of Operation - intended both for the general reader and the more experienced customer engineer. The approach used divorces the reader from the logic prints and explains internal operations with the aid of block and flow diagrams.

• Section V, Diagrams - this section is contained in Book 2 (publication number 82128200). The approach taken features detailed descriptions interlaced with the logic diagrams yielding a second "theory. II

• Section VI, Maintenance - detai led description of adjustment points as well as preventive maintenance procedures. For physical orientation, cross-reference Sections I and II.

• Section VII, Maintenance Aids - additional miscellaneous information which might aid in servicing the controller.

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217

FOREWORD (CONT)

NOTE

Refer to the 217-2 Equipment Controller Parts List (publ ication number 82128400) for parts information.

The characteristic feature of th is controller is its abi I ity to increase its data processing scope by adding other peripheral units. A special adapter kit is required for each i/o device added. These adapters consist mainly of additional logic boards to be installed in the controller logic rack. Accordingly, both books maki ng up this Customer Engi neering publ ication describe the adapters in detai I. For specifications on the units, consult the associated documentation supplied.

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217

TABLE OF CONTENTS

Section Page

I GE NERAL DE SCRIPTION

Physical Data

1-3

Environmental Data

1-4

Electrical Data

1-4

II OPERATION AND PROGRAMMING

III INSTALLATION AND CHECKOUT

PART A - BASIC CONFIGURATION

Unpacking

3-1

Cabling

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Section

IV

217

TAB LEO F CON TEN T S ( CON T )

THEORY OF OPERATION

PART A - BASIC CONFIGURATION

Main Timing Master Clock Timing Chain Pass Counter Clock Pulses Display Control

Window

Display Register Position Counters Keyboard Control

B~ckspace

Skip _Line Skip

Carriage Return Reset Clear Send Interrupt Print Repeat Line Counter Symbol Gene rator Interface

Initial Contact Automati c Answering Data Transmission Message Format Rece ive Operation

Word Parity Message Parity

Poll Message Alert Message

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217

T AS LE OF CO NTENTS (CONT)

Section Page

IV Write Message

4-38

Reset- Write and CI ear- Write Messages

4-41

Diagnostic Write Message

4-41

Transmit Operation

4-43

Acknowl edge Message

4-45

Reject Message

4-46

Error Message

4-46

Read Message

4-47

Redundant Responses

4-51

PART S - CARD READER ADAPTER KIT

General Operation

4-3

Data Entry

4-7

Data Transfer

4-8

Load

4-8

List

4-9

Test

4-9

Skip

4-10

Interrupt

4-10

PART C - TYPEWRITER ADAPTER KIT

General Operation

4-2

Uppercase/Lowercase

4-2

Space

4-4

Carriage Return

4-5

Data Translations

4-8

Printout Termination

4-8

Interrupt

4-10

PART D - LINE PRINTER ADAPTER KIT

General Operation

4-1

Line Truncation

4-3

Format Control

4-5

Printout Term ination

4-7

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217

TABLE OF CONTENTS (CONT)

Section Page

N

Test Mode 4-7

Interrupt 4-7

PART E - CARD READER ADAPTER KIT

General Operation 4-3

Data Entry 4-6

Data Transfer 4-6

Load 4-6

List 4-7

Interrupt 4-7

Test 4-8

V DIAGRAMS

VI MAINTENANCE

Preventive Maintenance 6-1

Test Equipment Required 6-1

Corrective Maintenance 6-2

Video Pulse Adjustments 6-3

Ramp Generator Adjustments 6-5

Automatic Answering Adjustment 6-5

Delay-Line Memory Adjustment 6-7

Power Supply Adjustments 6-8

Power Supply Troubleshooting 6-10

+ 5- Vol t Supply 6-10

+ 20-Volt Supply 6-11

- 20-Volt Supply 6-12

Transformer 6-13

VII

-

MAINTENANCE AIDS

Symbol Timing and Formation Matrix 7-1

Card Schematic Diagrams and Assembly Drawings 7-3

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217

SECTION I

GENERAL DESCRIPTION

The basic Equipment Controller is designed primari Iy for Display Station entry and retrieval communications with a central processing site (data source). All data entered from the Display Station keyboard and all communications with the data source form a crt display.

Equipment Controller design also allows for the modular addition of other entry or retrieval devices to the basic configuration. These add itional devices include a card reader and/or a printer. The printer may be a typewriter or a high-speed line printer. For each unit added to the basic configuration, a special adapter kit must be installed in the Equipment Controller.

Each adapter kit contains a 1 O-mi lIisecond delay-line memory and the logic necessary to form a module governing the operation of the assoc iated unit. This memory, in addition to providing data storage facilities for the associated unit, adds to the overall buffering network. The basic module governing Display Station opera-tion also contains a delay-line memory so the overall buffering scheme in the control-ler appears as:

DATA SOURCE

82128100

EQUIPMENT

----,-- CONTROLLER 1 4 - -... ,

INTERFACE

DISPLAY STATION

DISPLAY MODULE

Bu fferi ng Sc heme

1-1

MAY OR MAY NOT CONTAIN ADDITIONAL

BUFFERING

ADAPTER KIT

(MODULE)

\

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General Description

217

Section I

The next group of illustrations point out the structure of the controller; co II i ng out suc h i terns as delay lines I power supp Iy, etc.

POWER SUPPLY (SWING-OUT DOOR)

DISPLAY STATION OUTLET AND FUSES FOR DISPLAY STATION AND A-C INPUT

Rear View (Panel Removed)

SYMBOL GENERATOR (DIODES,DIODE DRIVERS

AND DIODE RECEIVERS)

DELAY LINES DL I-DISPLAY DL 2-ADAPTER DL 3-ADAPTER

ROWA

LOGIC CHASSIS (SIDE VIEW) ROW B

POWER CABLING TERMINAL STRIP

LOGIC CHASSIS ROW A

ROW B

SWITCH PANEL

Left S ide Vi ew (Pane I Removed)

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Section I

+20-VOL T D-C OUTPUT (F USE AND T EST POI NTS)

-20-VOL T D-C OUTPUT (FUSE AND TEST POINTS)

+5-VOL T D-C OUTPUT (FUSE AND TEST POINTS)

PHYSICAL DATA.

217

_{General Description}

____ SWiTCH/INDiCATOR PANEL

Right Side View (Panel Removed)

POWER SUPPLY (SWI NG-OUT DOOR)

The Equipment Controller may be located as desired within the limitations of size, weight, and environmental conditions. Dimensions and weight are shown in the next illustration.

WEIGHT-I25 POUNDS

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General Description 217 Section I

ENVIRONMENTAL DATA.

Temperature, relative humidity, and altitude limitations under both opera-tiona I and nonoperaopera-tional conditions are I isted next. Operaopera-tional condition means that the unit should function properly if normal operating procedures are followed. Nonoperational condition means that the unit is capable of operation after storage and transit under listed environmental conditions, providing it is properly packaged.

ENVIRONMENT AL CONDITIONS

CONDITION OPERATIONAL NONOPERATIONAL

Temperature +60 to +85

F

- 30 to + 150

F

Relative Humidity 10 to 900₁₀ _{5 to 100%} (includes condensation)

Altitude - 1 000 to + 1 0, 000 ft - 1 000 to + 15, 000 ft

The Equipment Controller uses ambient air for cooling by radiation and convection, therefore, air ducts are not necessary. Heat dissipation is about 441

Btu per hour when equipment is in operation.

ELECTRICAL DATA.

A-c power requirements for the Equipment Controller are as follows:

105 to 125 vac, 47 to 400 hertzr 1.0 ampere

(60-hertz i nsta lIations)

OR

210 to 250 vac, 47 to 400 hertz, 0.5 ampere (50-hertz i nsta Ilations)

D-c outputs are fused on the power supply door (see page 1-3). The follow-ing list gives fuse types and current ratfollow-ings.

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Section I

TYPE

3AB AGC 3AG

217 Genera I Description

D-C OUTPUT FUSES

SIZE (Amperes)

8.0 3.0 1 .5

DESCRIPTION

+5-volt d-c output (F1) - 20-vo It d-c output (F2) + 20-volt d-c output (F3)

Display Station and controller power supply a-c input power is fed through the two fuses on a box in the lower rear of the controller (see page 1-2). Modem a-c input passes through the fuse in the modem cubicle (see page 1-2). The next two lists show fuse types and current ratings for both 60- and 50-hertz installationse

TYPE

3AG Sio Blo 3AG

510

Blo 3AG

510

Blo

TYPE

MDX Sio Blo MDA Sio Blo MDL Sio Blo

82128100

60-HERTZ A-C INPUT FUSES

SIZE (Amperes)

2.0 5.0 0.5

DESCRIPTION

Display Station a-c input (F1) Power Supply a-c input (F2) Modem a-c input (F3)

50-HERTZ A-C INPUT FUSES

SIZE (Amperes)

1.25 3.0 0.5

1-5

DESCRIPTION

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217

SECTION II

OPERATION AND PROGRAMMING

This section provides supplemental information to the discussion of the Equipment Controller's role in the Remote User Terminal operation and programming presented in the Reference Manual. The supplemental information concerns itself only with the operation of controls located on or within the Equipment Controller.

Programming is generally on a total equipment basis which is the fundamental approach of the Reference Manua

I.

Two switch panels govern most of the controller operations. One of these is located on the right rear corner of the toble top and is directly accessible to the operator.

Switch/Indicator Panel

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Operation and Programming

SWITCH/INDICATOR

LINE/BLOCK

POWER ON

ON LINE

MAN REL

(Manua I Rei ease)

LIST

LOAD

217 Section II

FUNCTION

Alternate action, illuminated pushbutton - when LINE is illuminated, the line indicator is used in communications and message composition. BLOCK position prevents use of the line indicator.

An alternate action, i lIumi nated pushbutton. De-pression resu Its in appl ication of primary power to the Equipment Controller and an initial master clear of logic. The lens is illuminated while power is on. A second depression turns power off.

Indicator illuminates when the equipment is trans-mitting or receiving information.

A momentary action, lighted pushbutton unlocks the keyboard for operator use when activated. In addi-tion, the entry marker is reset without affecting dis-played data and the interface is cleared.

A momentary action, lighted pushbutton which ini-tiates a read operation from the card reader to the printer. Data is not displayed or transmitted to the data source. Completion of printout extinguishes the light a~ returns the Equ ipment Controller to an inactive state.

A momentary action, I ighted pushbutton enables a read operation from the card reader to be performed. Subsequent data transm issions are under control of the data source. Read operation completion turns off the light.

The remaining set of switches are on the bottom of the logic assembly. This assembly is accessible through the left panel of the Equipment Controller cabinet

(see page 1-2).

Logic Assembly Switches

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Section II

SWITCH

INT BCD/EXT BCD

ALARM TEST

AUTO ANSWERING

ERROR ENABLE/DISABLE

POLL NORMAL/WAIT

2 WIRE/4 WIRE

READER TEST/MC

PRINTER TEST

82128100

217

Operation and Programm ing

FUNCTION

INT BCD position - enables transmission and interpretation of received data in internal binary coded decimal format. EXT BCD position

-=-enableS-transmission and interpretation of received data in external ,!:inary coded ~ecimal format.

When placed in the ON position, this switch acti-vates the ALERT light and alarm on the Display Station. The alarm cannot be turned off at the Display Station keyboard. This switch serves as a maintenance feature.

Activation of this switch allows the controller to operate with the automatic answering feature.

ENABLE position - allows transm ission of an error message, shou Id an error condition arise. DISABLE position - blocks tra'nsmission of any pend i ng error messages.

NORMAL position - controller transmits a reject message in response to a poll if no read message is pending. WAIT position - controller transmits an acknowledge message in response to a poll if no read message is pending. Any subse-quent read message is then transm itted without the aid of another poll, as long as no other message is received in the meantime.

Allows modem connection in either 2- or 4-wire half duplex.

TEST position - initiates a read operation at the card reader. Data is transferred to the display memory for observation on the crt. MC position -momentary action in wh ich controller and adapter kits are master cleared.

Prevents completion of print operation (except for a manual reJease or master clear condition) caus-ing continual printout ofa message while switch is in the ON position.

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217

SECTION III

INSTALLATION AND CHECKOUT

This section contains unpacking, assembly, and checkout information for the Equipment Controller including adapter kits. A rigid preshipment, qual ity control check ensures proper performance. If any problems occur, refer to Section VI, Mai ntenance, in this book.

To facilitate the use of test equipment during periods of maintenance, Control Data requires that a convenience outlet be available within 15 feet of each system component cabinet. The outlets may be located in the walls or ra ised floor pane Is of the equ i pment room and must not be obstructed by storage racks or other furniture. The receptacles shall be of the single-phase grounded type, installed according to local electrical codes. For 60-hertz installations, the nominal voltage shall be 120 volts. For 50-hertz installations, the nominal voltage shall be 220, 230, or 240 volts as dictated by the single-phase power available at the site.

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PART A

BASIC CONFIGURATION

Covering

Equipment Controllers:

FC710-A FC710-B FC711-A FC711-B

For use with Display Stations:

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Section III

217

Installation and Checkout Basic Configuration

UNPACKING.

The Equipment Controller is shipped in a cardboard carton attached to a special skid. Remove the carton and all tape, straps, and padding. The packing materials, containers, and skid should be saved for reuse in event of reshipment.

Remove the Equipment Controller side panels and check to see that all com-ponent mounting hardware is securely fastened, and that all boards are securely inserted in their respective connectors. Check the power supply door for freedom of movement.

CABLING.

One end of an 8-foot modem cable is wired directly into the Equipment Controller logic assembly. The other end is terminated in a small gray connector which plugs into the receptacle provided on the modem. Following are the modem cable pin assignments.

MODEM DATA CABLE

PIN DESIGNATION SIGNAL ORIGIN

1 Protective Ground Modem and Controller

2 Transmitted Data Controller

3 Received Data Modem

4 Request to Send Controller

5 Clear to Send Modem

6 Data Set Ready Modem

7 Signal Ground Modem and Controller

8 Data Carrier Detector Modem

9 Reserved for Data Set Testing Not Used

10 Reserved for Data Set Testing Not Used

11 Not Used

12 . Not Used

13 Not Used

14 New Synchronization Not Used

15 Transmitter Signal Element Timing Modem

16 Dibit Clock Transmit Not Used

17 Receiver Signal Element Timing Modem

18 Dibit Clock Receive Not Used

19 Not Used

20 Data Terminal Ready Controller

21 Not Used

22 Ring Indicator Modem

23 Not Used

24 Transmitter Signal Element Timing Not Used (External Timing Input)

25 Not Used

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Installation and Checkout

MODEM A-C POWER

CABLE

TO PHONE

LINES - - t -_ _

FROM MODEM

217

-Basic Configuration

60 HERTZ INSTALLATION

(REAR VIEW)

Section III

MODEM ----,-DATA

CABLE

J2 is not used in 50-hertz installations. In this case, the modem power cable must be connected to terminal strip TB3 as shown in the next illustration. The terminal strip is on the front side of the pane I so the cab Ie must be routed through one of the holes.

TB3 YELLOW

GREY

220V---r---~~~ GROUND

0

I

MODEM DATA

CABLE

Part A

NEUTRAL

CONNECTOR PANEL - 50 HERTZ

(FRONT VIEW)

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Section III 217 Insta Ilation and Checkout Basic Configuration

One end of a 6-foot Display Station data cable is wired directly into the logic assembly. The other end contains a large metal connector for the receptacle at the rear of the Display Station. Following are the Display Station data cable pin assignments. The cable consists of 21 twisted pair and four coaxial lines. Unlisted pi n numbers are not used.

DISPLAY STATION DATA CABLE

PIN NO.

1

2

3

4 5 7 8 9 10 . 11

12 13 14 15 16 18 19 20 21

22

23

24 25 26 27 34 38 40 SIGNAL

Data Bit 0 Data Bit 1 Data Bit 2 Data Bit 3

Horizontal (Coaxial Line) Vertical (Coaxial Line) Data Bit 4

Data Bit 5 Data Bit 6 Clear Key Strobe Repeat Key Function Strobe Send Index Key Interrupt Key Ground Ground Ground Ground Ground Ground Alarm Disable Alert Light

U nattended/ Attended Light Unattended/Attended Switch Alert Alarm

Video (Coaxial Line) Diddle (Coaxial Line)

The Display Station data and a-c power cables must be routed through the hole in the lower rear panel. For 60-hertz installation, connect the power cable to J 1 at the bottom. The cable is connected to TB2 at the same point for 50-hertz i nsta lIati ons.

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HOLE IN BACK

PANEL

DISPLAY STATION A-C POWER

CABLE

60 HERTZ

FI F2

(;j

(!)

MONITOR

Part A

217

Basic Configuration

DISPLAY STATION

(REAR VIEW)

TO DISPLAY

STATION {

WHITE

BLACK

GREEN

Cabling Diagram

Section III

DISPLAY STATION

, - - DATA CABLE

HOLE IN BACK

PANEL

50 HERTZ

FI F2

(!j

MONITOR

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Section III 217 Insta lIati on and Chec kout Basic Configuration

The Equ ipment Controller a-c power cab Ie and adapter kit data cab les are routed through the bottom. Adapter kit connections are described in the applicable Reference/Customer Engineering Manua Is. The a-c power cab Ie requ ires a standard sing Ie-phase grounded out let for 60-hertz insta I lations . For 50-hertz insta Ilations, the cable is· not terminated in a connector. The power cable consists of 3 18-gauge wires, and for 50-hertz insta Ilations, the wire assignments are:

ASSEMBLY.

Black - 220 volts White Neutral Green . - Ground

The Equ ipment Controller is sh ipped fu Ily assembled. All that remains is to install interconnecting cables.

1 . Refer to the Disp lay Station Reference/Customer Engineering Manua I (publication no. 82136300) for monitor assembly instructions.

2. Plug in Display Station data cable.

3. Attach Disp lay Station a-c power cable.

4.

Plug in modem data cables.

5. Connect modem power cable.

CAUTION

Modem power cab Ie shou rd not be connected before data cab les are attached.

6. Place modem in cubicle provided in controller.

7.

Reseat all logic cards.

8. Connect Equipment Controller a-c power cable.

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Installation and Checkout 217 Section III Basic Configuration

The lower four bit positions of the controller site address are determined by the four slide switches on the board in jack B 12. The least significant bit is the lowest switch position whereas the most significant bit is the top switch position. A logical 0 is entered in a bit position when the switch is in the outside position. System requirements determine what the actual address should be.

8

01 02 03 04 05 06 07 08 09 10 II 12 13 14 15 16

LOGIC RACK

SITE

---~ ADDRESS

SWITCHES

The final steps involve the switch panel located on the logic rack (see description in Section II). System requirements determine the positions of most of these switches.

Part A

1 • The position of the INT/EXT BCD switch is determined by the code set used at the central processing site.

2.

AUTO ANSWERING may only be used if the modems are capable of such operation.

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Section III

217

Insta Ilation and Checkout Basic Configuration

3. Place the ERROR ENABLE/DISABLE switch in the ENABLE position if the data sou rce recogn izes an error message. Otherwise, use the DISABLE position.

4. POLL NORMAL/WAIT can be placed in the WAIT position only if the terminal is the only site on the common carrier.

5. The 2-WIRE/4-WIRE switch should be in a position corresponding to the modem strapping option employed.

6. Use the ALARM TEST switch to turn on the Display Station alert alarm for volume adjustment purposes (see Display Station Reference/Customer Engineering Manua I).

7. READER TEST and PRINTER TEST switches are explained in associated adapter kit Reference/Customer Eng ineering pub Ii cati ons.

CHECKOUT.

The following chart depicts a simplified checkout procedure assuming all cables have been properly installed. Use Sections VI and VII and the Display Station Reference/Customer Engineering Manual in the event any adjustments are required or malfunctions occur.

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217

Section III Basic Configuration

DEPRESS POWER ON

SWITCH/ INDICATOR

PANEL

FILL RASTER WITH VARIOUS SYMBOLS INDICATOR ILLUMINATED YES ROTATE ON/OFFj INTENSITY CLOCKWISE RASTER VISIBLE

FUSE ON REAR OF DISPLAY STATION OK

NO CHECK OUT

PERFORMANCE THROUGH

CENTRAL PROCESSING

SITE SEE VIDEO PULSE AND DELAY-LINE ADJUSTMENTS IN SECTION VI AS WELL AS ADJUSTMENTS SPECIFIED IN THE DISPLAY STATION

REF ICE MANUAL

NO

REPLACE FUSE

A-C INPUT

(F2)

FUSE OK

YES YES CHECK INPUT POWER NO REPLACE FUSE REPLACE LAMP

r

-I

I I

I

DISPLAY FJ

6 - - - ,

I I

I

I I

F2 I

..J

MONITOR

STATION fUSE REPLACE

IN CONTROLLER FUSE

(FJ) OK

YES

SEE POWER SUPPLY ADJUSTMENTS

IN SECTION VI

CHECK RAMP GENERATORS ADJUSTMENT

(SEE SECTION VI)

Simplified Checkout Procedure

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PART B

CARD READER ADAPTER KIT

Equipment Numbers

FE 1 05-A FE105-B FE106-A FE106-B

For use with the 224-1 Card Reader Station, Equipment Numbers:

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Section III 217

Typewriter Adapter Kit

An adapter kit must be installed if the controller is to drive a 218-1 Type-writer Station. The following illustration points out adapter kit board, cable, and

jumper locations in the controller logic rack. Refer to the 218-1 Typewriter Station Reference/Customer Eng.ineering Manual for specificat"ions on the typewriter.

16 17 18 19 20 21 22 23 24 25 26 27

w ...J

a::: a:::

0 0 0 0 0 0 m

w w 0 <t

a. a. <l IJ.. (!) _<l _J: ₀

«

u _B

:!: :!:

~ (I) (I)

«

(I) (I) _<l <t

~ ~ I'- I'- I'- I'- I'-

l"-) ...., ...., t-<t

0

Typewriter Adapter Placement

CABLING.

One end of the 15-foot typewriter data cable terminates in a 62-pin board while the other terminates for connection to the typewriter. Insert the board end in

B27. The next I ist calls out pin assignments for the cable. Odd-numbered board pins are on the soldered side with even numbers on the other side. Pin numbering is sequential from top to bottom. As an example, the upper pin on the soldered side is pin 1, while the adjacent pin on the other side is pin 2. Unlisted pin numbers are not used.

CHECKOUT.

An operational check qf the typewriter can be performed locally through the use of the Display Station.

1. Equipment Controller POWER ON to ON (illuminated) position.

2. Display Station ON/OFF/INTENSITY to ON position.

3. Typewriter ON/OFF rocker switch to ON position.

4.

Feed paper from tray up through tractor assembly.

5. Compose message using Display Station keyboard.

6. Depress AUX SEND key when composition is completed.

7. Displayed message is typed up to the E2

C)

symbol as an image of the crt display.

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DESIGNATION

Norma Ily Open Normally Closed Carriage Return Space

Upper Case Lower Case Rl R2 R2A R5 Tl T2 CK

Keyboard Lock End of line +20 Volts

Paper Low (Ready) Ground

- 50-Volt Ground Return

217

Typewriter Adapter Kit

TYPEWRITER DATA CABLE

CONNECTOR BOARD

PIN PIN

A 3

C 5

E 7

F

8

H 11

J 12

K 13

L 14

M

15

N 16

P 17

R 18

S 19

T 20

V 56

X 33

Y 25

Z 31

a 27

Section III

SIGNAL ORIGIN

Typewriter Typewriter Controller t Controller Typewriter Controller Typewriter

---If a card reader is a member of the configuration, a local printout of punched card data is possible (without display). In th is case, the Display Station is not used since the message consists of punched cards. After making the reader operational and loading cards, all that remains is to depress the LIST switch. Printout is in 12-card batches until the hopper is empty. Each print line is one 12-card in length (up to 80 symbols).

A final check can be made via programming at the central processing site. Each write message received (ending with escape and E2 codes) initiates a printout which is an exact image of the crt presentation.

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Section III 217 Installation and Checkout Card Reader Adapter Kit

If a printer is also included in the configuration, it may also be used to monitor reader operation. The same steps should be followed. Instead of rotating the Display Station ON/OFF/INTENSITY control, ensure the printer is ready. Then, depress the LIST switch on the controller table top in place of using the READER TEST/MC switch. With this method, 12-card batches of data will be read and printed {without display} until the hopper is empty. The Display Station keyboard remains unlocked during this interval.

The fi nal check is via programm ing at the central processing site {LOAD mode}. Here, each write message ending with an escape code followed by E3 ini-tiates transmission of a 12-card batch of data. A simu Itaneous display occurs. The Display Station keyboard is locked out during LOAD mode. A write message from the data source (ending with an E1 code), master clear, or manual release is required to perform the release.

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PART C

TYPEWRITER ADAPTER KIT

Equipment Numbers

FF305-A FF305-B FF306-A FF306-B

For use with the 218-1 Typewriter Stat ion, Equ i pment Numbers:

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Section III 217 Installation and Checkout

Li ne Pri nter Adapter Kit

In order to drive a 222 line Printer, the Equipment Controller must contain an adapter kit. Board, cable, and jumper locations in the logic rack are shown next. For information on the line printer, reference the 222 Line Printer Controller Reference/Customer Engineering Manual.

16 17 18 19 20 21 22 23 24 25 26 27

UJ ....J

a:: a:: ₀ m

UJ UJ 0 0 0 0 <!

a.. a.. I- (f) :::J 0 ... 0

B

~ ~ a:l U a:l (D (D

«

)

::::>

.., ..,

::::> I"- 00 f'- I'- I"-

...

<!

0

Line Printer Adapter Placement

CABLING.

One end of a 15-foot line printer cable connects to a 62-pin board while the other terminates for connection to the line printer. Insert the board end in B27.

Followi ng are pi n assignments for the cable. Odd-numbered board pi n~ are on the soldered side with even numbers on the other side. Pin numbering is sequential from top to bottom. For example, the upper pin on the soldered side is pin 1 while the adjacent pin on the other side is pin 2. Unlisted pin numbers are not used.

CHECKOUT.

The following procedure should be observed to locally check line printer operation.

2. Displdy Station ON/OFF/INTENSITY to ON position.

3.

Printer POWER ON switch to ON position.

4.

Depress printer PAGE EJECT.

5. Insert paper in tractor assembly.

6. Activate START button.

7. Compose message using Display Station keyboard.

(44)

Installation and Checkout 217 Section III Line Printer Adapter Kit

8. Depress AUX SEND when composition is complete.

9. Displayed message is printed up to the E2

C)

symbol.

LINE PRINTER DATA CABLE

DESIGNATION CONNECTOR BOARD SIGNAL ORIGIN

PIN PIN

Data Bit 0 A 3 Controller

Data Bit 1 B 4

Data Bit 2 C 5

Data Bit 3 D 6

Data Bit 4 E 7

Data Bit 5 F 8

Data Bit 6 H 11 Contro.ller

Ground b 29

Informati on Ready R 18 Controller

Output Resume S 19 Printer

Master C

I

ear U 21 Controller

Ready

W

23 Printer

Print Mode X 24 Controller

Not 136 Colun.n

V

22 Printer

The PRINTER TEST switch on the logic rack may be used to cause a con-tinual printout of the same message. This switch blocks recognition of the E2 symbol.

If a card reader is avai lable, punched card data may also be printed locally (without display). After making the reader operational and loading cards, all that remai ns is to depress the LIST switch. Pri ntout is in 12-carcl batches unti

I

the hopper is empty. Each print line is one card in length (up to 80 symbols). Here, again, the PRINTER TEST switch may be used.

The final step is to check printer operation through the central processing site. Each write message received (ending with escape and E2 codes) initiates a

printout wh ich is an exact duplicate of the crt presentation. The PRINTER TEST switch may be used in this instance also.

(45)

PART D

LINE PRINTER ADAPTER KIT

Equipment Numbers

FF512-A FF512-B FF513-A FF513-B FF514-A FF514-B FF515-A FF515-B

For use with the 222- 1 and 222-2

Line Printer Stations, equi pment numbers:

(46)

(47)

In the event a 224-1 Card Reader is part of the configuration, a card reader adapter kit should be installed in the logic rack. The next chart shows the location of logic boards, jumper, and cable comprising the package. Refer to the 224-1 Card Reader Station Reference/Customer Engineering Manual for details on the reader.

01 02 03 04 05 06 07 08 09 10 \I 12 1

w ...J

ID

0 Cl Cl 0 0::: 0:::

« 0 0 _w _w

B u -:> <! m ::::> u 0 0.. 0..

en :J: :J: 0 :J: (l) _:!: _:!:

« I"- co ex> 00 ex> I"- ::::> ::::>

t- ...., ....,

«

0

Card Reader Adapter Placement

CABLING.

The data cab Ie for the card reader is 15 feet long and one end termi nates in a 62-pi n board wh i Ie the other end contai ns a rectangu lar connector. Insert the board end in location B01. The other end connects to the card reader. Follow i ng is a I ist of pin assignments for the cable. Odd-numbered board pins are on the soldered side of the board with even numbers on the other side. Pin numbering is sequential from top to bottom. As an example, the upper pin on the soldered side

is pin 1, while the adjacent pin on the other side is pin 2. Unlisted pin numbers are not used.

CHECKOUT.

The READER TEST/MC switch on the logic rack initiates an operational check of the reader. With the Display Station and Equipment Controller functioning prop-erly, punched card data may be monitored at the Disploy Station with the switch in the TEST position. During this period, the Display Station keyboard is locked out. A power on master clear or manual release is required to perform the release, once the switch has been taken out of the TEST position.

2. ON/OFF/INTENSITY control to ON position.

3.

READER TEST/MC switch to TEST position.

4. Load reader hopper with punched cards.

(48)

Insta Ilation and Checkout

217

Section III Card Reader Adapter Kit

5. Reader MAN/AUTO switch to AUTO position. 6. Reader ON/OFF switch to ON position. 7. Depress reader REG switch.

8. Punched cards wi II be read and d isp layed unti I the hopper is empty.

CARD READER DATA CABLE

PIN PIN

+5

Volts DC L, P, K

1, 2, 61

Controller

Register U

6

Card Reader

Skip

W

8

Not Skip X

11

Pressure Rollers Down

Card Reader

Escapement d

14

Controller

Ready s

23 I

Check Reader r

22 - 20

Volts DC E, M

29, 30

+20

Volts DC J

33

Controller

(49)

PART E

CARD READER ADAPTER KIT

Equ ipment Numbers

FE108-A FE108-B FE109-A FE109-B

For use with the 224-2 Card Reader Station, Equipment Numbers:

(50)

(51)

Section III

217

Installation and Checkout Card Reader Adapter Ki t

A 224-2 Card Reader Station becomes a member of the configuration when this adapter is properly installed. The next chart shows the location of logic boards, jumper, and cable comprising the package. Refer to the 224-2 Card Reader Station Reference/Customer Engineering Manual for details on the reader.

01 02 03 04 05 06 07 08 09 10 II 12 I

w ...J

al 0:: 0::

B U ct 0 _N 0 ₀ 0 _N _lL.0 _lL.0 0 _lL. ₀0 ₀0 _0..W LLI _0..

ct lL. _I'- _I'-U _I'-(!) _I'-U U _I'- U _I'- --, Cl) CD I'- ~ ~ :::> :::>

....

.,

ct

0

Card Reader Adapter Placement

CABLING.

The data cable for the card reader is 15 feet long and one end terminates in a 62-pin board. Insert the board end in location

BDl.

The other end connects to the card reader. Following is a list of pin assignments for the cable. Odd num-bered board pins are on the soldered side of the board with even numbers on the other side. Pin numbering is sequential from top to bottom. As an example, the upper pin on the soldered side is pin 1, while the adjacent pin on the other side is pin 2. Unl isted pin numbers are not used.

CHECKOUT.

The READER TEST/MC switch on the logic rack initiates an operational check of the reader. With the Display Station and Equipment Controller function-ing properly, punched card data may be monitored at the Display Station with the switch in the TEST position. During th is period, the Display Station keyboard is

locked out.

A

power-on master clear or manual release is required to unlock the keyboard once the switch has been removed from the test position.

(52)

Installation and Checkout 217 Section III Card Reader Adapter Kit

CARD READER DATA CABLE

PIN PIN

Feed C 59 Controller

Ground H 60

Ready A 51 Reader

Ground E 52

Check Error D 58 Reader

Ground J 57

Strobe B 50 Reader

Ground F 49

End Data

M

07 Reader

Ground S 08

Channell K 14 Reader

Ground P 13

Channel 2 N 19 Reader

Ground T 20

Channel 3 L 22 Reader

Ground R 21

Channel 4

W

25 Reader

Ground

-

a 26

Channel 5

U

28 Reader

Ground

Y

27

Channel 6 X 35 Reader

Ground

b

36

05

Channel 12

r-

03 Reader

Ground

v

04

Ground j5' 09

Ground IT 31

Ground

z

32

Ground DD 54

(53)

2. ON/OFF/INTENSITY control to ON position.

3. READER TEST/MC switch to TEST position.

4.

Load reader hopper with punched cards.

5.

Reader MAN/AUTO switch to AUTO position.

6. Reader ON/OFF switch on front panel to the ON (up) position. 7. Depress READY/CHECK (READY should light).

8. Depress FEED/ERROR (FEED should light).

9. Punched cards wi

II

be read and displayed until the hopper is empty or an error occurs. Since a hopper-empty situation is created before the

last card can be scanned, this card should be blank or contain non-essential information.

If a printer is also included in the configuration, it may also be used to monitor reader operation. The same steps should be followed. However, instead of rotating the Display Station ON/OFF/INTENSITY control, ensure the printer is ready. Then, depress the LIST switch on the controller table top in place of using the READER TEST/MC switch. With this method, 12-card batches of data wi

II

be read and printed (without display) unti

I

the hopper is empty. The Display Station keyboard remains unlocked during this period.

The final check is via programming at the central processing site (LOAD mode). Here, each write message ending with an escape and E3 code initiates transmission of a 12-card batch of data. A simultaneous display occurs. The Dis-play Station keyboard is locked out during LOAD mode. A write from the data source (ending with an El code), master clear, or manual release is required to unlock the keyboard.

(54)

(55)

217

SECTION IV

THEORY OF OPERATION

The approach taken in the theory of operation for the Equipment Controller is from a functional viewpoint. Such a systematic approach eliminates the necessity for considering each of the mu Ititude of relationships shown in the logical diagrams

(Section V, Book 2) •

•

With this approach, it is only necessary to consider the general structure of the controller in order to develop a concept of the factors which govern operation of the remote terminal. The basic structure of the controller features the functional areas of INTERFACE, MAIN TIMING, SYMBOL GENERATION, and DISPLAY CONTROL. Other areas discussed are adapter kits containing logic inserted in the controller to permit attachment of additional input/output devices.

(56)

(57)

PART A

BASIC CONFIGURATION

Covering

Equ i pment Contro Ilers:

FC7l0-A FC710-B FC7ll-A FC711-B

and for use with Display Stations:

(58)

(59)

Section IV 217 Theory of Operation Basic Configuration

In its basic configuration, the 217-2 Equipment Controller has been designed to control Display Station crt disploys, process Display Station keyboard signals, and handle communications with the central processing site (data source). Actually, a given controller may be one of four types. The differences appear in display page format (number of symbols per line and number of lines per page) and power require-ments (120 volt, 60 hertz or 220 volt, 50 hertz).

EQUIPMENT NUMBER

FC710-A FC710-B FC711-A FC711-B

PAGE FORMAT

20 Lines of 50 Symbols 20 Li nes of 50 Symbols 13 Li nes of 80 Symbo Is 13 Li nes of 80 Symbo Is

POWER REQUIREMENTS

120 Volts, 60 Hertz 220 Volts, 50 Hertz 120 Volts, 60 Hertz 220 Volts, 50 Hertz

217-2 Equipment Controller with Display Station

(60)

The(lr)' of Operation

217

Section IV

Basic Configuration

W

_t

~

::>

-0>

t;:

C 0

U

I I

u

.;;;

0

co

s~

.~j ~

5

-.L

!!i

I!!

_I_w=

' - - - + - - 1 ~!;

t

I

10Il0l

I

(61)

MAIN TIMING.

Equipment Controller internal timing is based on the symbol transfer interval (symbol time), or time required to display one symbol. This interval is 16.8 micro-seconds long and is formed by 84 200-nanosecond pu Ises. These pu Ises are labe led time 1 (t1) through time 84 (t84) and are formed by a network consisting of a master clock, timing chain, and pass counter. Following is an illustration showing the interrelationships involved in this timing network.

COUNTS TO 12

MASTER CLOCK.

MASTER CLOCK

- ,0A AND %B

TIMING CHAIN

CLOCK PULSES

7 x 12

-

84

PULSES

Timing Block Diagram

PASS COUNTER

COUNTS

-T07

An oscillator circuit and mod 8 counter form the master clock network shown next. The mod 8 counter converts the 20

MHz

square wave from the crystal-controlled oscillator into two continuous streams of 200-nanosecond pulses. These two outputs are 180 degrees out of phase, forming phase A and phase B of the master clock.

(62)

Theory of Operation 217 Section IV Basic Configuration

OSCILLATOR

---.-i

~ 50 NANOSECONDS

t

200 NANOSECONDS

MOD

8

COUNTER

Simpl ified Master Clock Operation

TIMING CHAIN.

Each 200-nanosecond pulse emanating from the master clock is registered in a timing chain. Actually, the chain is divided into two 6-step segments. Phase A

is registered in one half while the other half records phase B. In each half, the clock fflS set (for 400 nanoseconds) in succession with the previous ff clearing at the same time its succeeding 'ff sets. After the last ff in the entire chain sets, the sequence begins again. Since the sequences for each half are 180 degrees out of phase, they are displaced by 200 nanoseconds. Consequently, the fPs in one half overlap the fflS in the other half by 200 nanoseconds and twelve overlapping 400-nanosecond pulses are produced on each pass through the entire chain. These pulses are used to advance a pass counter and form the basic clock pulses by ANDing with the pass counter decoded outputs.

0A

-.J

-

U

- '

~I

TXXO/XXI

~I

r

L.

200

~

I

400

NANOSECONDS ~ ~ NANOSECONDS

--u-y

TXX2/XX3

~r---.

{

I

08

Timing Chain Overlapping

(63)

Section

IV

217 Theory of Operation Basic Configuration

PASS COUNTER.

Each pass through the tim ing chain increments the pass counter. This counter is initially cleared by the power-on master clear condition. Advent of the first phase B during each pass of the timing chain allows the pass counter to advance (a count of 6 is skipped). On a count of 7, the pass counter clears and begins again. The seven complete passes yield 42 overlapping 400-nanosecond pu Ises, the amount required for one complete symbol time.

CLOCK PULSES.

Outputs of the timing chain and pass counter are ANDed whenever necessary to form the basic clock pulses. This process identifies each clock pulse by its rela-tive position in the symbol transfer interval. The assigned positions are t1 through t84. Since sequential pulses overlap one another by 200 nanoseconds, the assigned positions for the pulses must also overlap. Consequently, any discrete 400-nanosecond pu Ise has two time positions; such as t1/t2, t2/t3, etc. Each time position then has a value of 200 nanoseconds and the 16.8-microsecond requirement for a symbol trans-fer interval is established. The following diagram illustrates the relationship between clock pulses formed by two successive timing chain steps.

82128100

-TXX2/XX3

AND

PASS 0 - - - . . . I I I

I

TXIO/XII

t2 I

(200 NANOSECON£?:~) ~

!

I I

I I I

I t2/t3

AND

Clock Pulse Derivation

(64)

DISPLAY CONTROL.

The display module uses a magnetostrictive delay line with an approximate length of 10 milliseconds for temporary data storage and buffering purposes. Data entering and leaving the delay I ine may be from:

• The card reader for transfer to the modem. • The Display Station keyboard.

• The modem for display alone or display and printout.

Each word is written into and read out of the delay line in serial, bit by bit, and displayed on the Display Station crt. Data is updated or changed between the time

it is read out and the time it is rewritten. Two passes through the delay I ine are required to complete one full scan ofa display page. Since two passes are required, upper and lower-half display page data must be interlaced in memory. Following is a block diagram representing the display control area in the Equipment Controller.

As already established, basic machine timing utilizes a symbol transfer inter-val (symbol time) of 16.8 microseconds. This means that the delay line must supply one symbol every symbol time. Each symbol time is divided into 16 equal divisions of 1.05 microseconds, allowing two 8-bit words (7 bits plus a marker bit) to be stored during the same 16.8-microsecond interval. The two words are displaced on the crt raster by one-half page (including retrace time). Hence, the first position of line 1 in a 20 by 50 format is interlaced with the first position in line 11. In a 13 by 80 format, the first position in line 1 interlaces with the 46th position in line 7.

WINDOW.

Data bits leaving the delay line pass through the read ff and shift into a 17-bit window every 1.05 microseconds. This action provides parallel assembly of two interlaced 8-bit words. The window shift pulses are provided by the mod 21 counter. A 150-nanosecond pulse is provided by this counter every 1.05 micro-seconds. The counter is cleared by a power-on master clear and regulated by the crysta

I

osc i Ilator.

Access is provided to one word, in the window, between successive window shift pulses. Only one word is available for gating from the window (to the display register) during each symbol time. This stipulation is necessary in order to provide a relationship between a word position in memory and its image on the crt raster.

(65)

READER ADAPTER MEMORY

•

DISPLAY MEMORY PRINTER ADAPTER MEMORY X COUNTER

-DISPLAY STATION KEYBOARD

AND INTERFACE DATA

+

7 BITS

~ WINDOW

-MAIN TItv\ING

I I

•

_Y

COUNTER

I

, +

DISPLAY STATION CRT MAIN TIMING

+

WINDOW CONTROL ~ ~ DISPLAY REGISTER KEYBOARD

-

CONTROL It LINE COUNTER

• t

SYMBOL GENERATOR

Display Control Block Diagram

-DISPLAY STATION KEYBOARD FUNCTIONS

In order to see how all symbol positions in the delay line may be referenced, it becomes necessary to ana Iyze the total tim i ng cycle of the mach i ne. Consideri ng an 80 by 13 raster, there are:

(80 symbols + 10 retrace) (13 lines)

+

1 retrace symbol position = 1171

symbol times in a complete machine timing cycle. Since two passes of the delay line are required, the total delay time (storage time) of the delay line and window

(66)

is 1171/2, or 585.5 symbol times. So, 1171 symbols must be stored at the rate of two symbols per symbol time. In a 20 by 50 format, th is wou Id become a:

(50 symbols + 9 retrace) (20 lines) + 1 retrace symbol position = 590.5

2

symbol times delay.

As seen by this analysis, there is a half-symbol skew to the delay line. This means that a symbol written in at the beginning of a specific symbol time is rewritten, during the next pass, one-half symbol time later. Referring to the 84-time symbol transfer interval, data is sampled for display during the 400-nanosecond interval, t4/t5. Hence, a symbol referenced during one pass at t4/t5 is referenced in the same window position at t46/t47 of the next pass (an 8.4-microsecond displacement) of the delay line. "Referencing" (at t4/t5 or t46/t47) indicates the 8 bits (including marker) in the last 8 positions in the window. The term does not necessari Iy mean a memory transfer has taken place but is used to indicate when a symbol appears in these positions in the window.

The next illustration indicates the contents of the window at t4/t5 and t46/t47. The interlaced symbols of line 11 (position 1) and line 1 (position 1) in the 20 by 50 format are assumed for this presentation. Actually, any two interlaced symbols would serve the same purpose. It should be emphasized, however, that transfer to the display register only occurs at t4/t5. This means that the symbol in the upper half of the window at t4/t5 cannot be transferred until the next pass.

Bits leaving the delay line are picked up by the read ff. Each bit then pro-ceeds through the window, leaving one ff and entering the next every 1.05 micro-seconds. Timing for the window shift operation is provided by the mod 21 counter.

Bits become available for transfer to the delay line when they enter the last ff 0N16)

in the window.

Each 8-bit symbol reserves one bit position for a marker. The marker is used to reference the symbol position avai lable for memory transfer (data entry or change). This is the symbol position directly above the entry marker on the display page. Since there is only one entry marker per display page, only one marker bit may reside in memory. Due to the ha

If

symbol time skew, a marker referenced in the last ff 0N16) in the window at t4/t5 of one pass is next referenced in the same ff

during the second pass at t46/t47. Since this ff can be sampled at both t4/t5 and t46/t47, search for the marker shou Id never take longer than one pass of the de lay line (approximately 10 milliseconds).

(67)

Section IV

217

Theory of Operation Basic Configuration

PASS 1 - T4/TS PASS 2 - T4/TS

WINDOW _{MARKER POSITION} _{MARKER POSITION}

,.

READ _WO

FF

FOR FOR

LIN E 1 - POSITION 2 LINE 11 - POSITION 2

W1

W2

W3

W4 _{DATA WORD}7~IT _{DATA WORD}7~IT

W5 _{LINE 11 - POSITION 1 LINE 1 - POSITION 2}IN IN

W6 DELAY

LINE W7

MARKER POSITION MARKER" POSITION

,

W8 FOR FOR

,..

LINE 11 - POSITION 1 LINE 1 - POSITION 2

W9

W10

TO Wll

DISPLAY ..

W12 REGISTER

AT

W13 T4/T5

7~IT 7~IT

DATA WORD DATA WORD

IN IN

LINE 1 - POSITION 1 LINE 11 - POSITION 1

W14

W15

'- "MARKER POSITION MARKER POSITION

~ WRITE

-

.

_W16

TERMS _{LINE 1 - POSITION 1 LINE 11 - POSITION 1}FOR FOR

WirxJow Shift Sequence

Probably the first question that comes to mind is how to enter data into the delay line or how to change that already present. Consider the following wirxJow re presen tat i on •

(68)

Theory of Operation

217

Basic Configuration

DATA ENTRY FROM KEYBOARD

OR DATA SOURCE WRITE MESSAGE

AFTER ENTRY MARKER

DETECTION AT T4/T5 OR T46/T47

BLOCK TO

ADVANCE MARKER WINDOW 26 ~ 25 =--+-24 ~ 23

--.

22

--..

21

--..

2° ~ FROM READER MEMORY W5 26 ___> 25 --+ 24

--.

23 ~ 22 ...::::..,.. 21 ~ 2° ~

Window Entry Sequence

TO DISPLAY REGISTER

EVERY T4/T5

TO PRINTER MEMORY PRINTER MEMORY WRITE PRINTER TRANSFER CONDITION

Section IV

Assuming the marker is detected at t4/t5 in W16, the 7 bits following are shifted in parallel to the display register. If new data is to be entered, original data must be erased and the marker must advance one symbol position. Disabling the "Display Memory Write" term and setting WO allows the marker to reference the

(69)

next sequential symbol position while clearing W9 through W15 erases the original word. When the next window shift pulse is received, the new 7-bit word is inserted

in the last 7 window positions (W10 through W16). However, since dis'play can only occur at t4/t5, this symbol must wait for two more passes (20 mi Iliseconds) before it is transferred to the display register.

The characteristic feature of th is window is that data may enter at either t46/t47 or t4/t5. Hence, even though transfer to the display register occurs at t4/t5, data may be entered into the last 7 wi ndow positions following entry marker detection at t46/t47. Subsequent display then occurs one pass (10 mi II iseconds)

later when these bits appear in positions W9 through W 15 at t4/t5.

Entry through the window is possible only for the Display Station keyboard and information received in write messages. Memory transfer from the reader adapter kit is a direct feed through the "Display Memory Write" term. Transfer to the printer adapter kit memory occurs in much the same manner.

DISPLAY REGISTER.

Data to be displayed is gated in parallel from window positions W9 through W 15 to a 7 fl ip-flop display register at t4/t5 of each symbol time, regard less of whether the marker is sensed. With the one-half symbol skew, data in the lower window positions at t46/t47 of the first pass arrives in the same positions at t4/t5 of the second pass. The display register is cleared each t84/t1 allowing entry of the next word. Information in the display register is decoded and transferred to a sym-bol generation network for ultimate crt display. In this way, two passes through the delay I ine enable all stored symbols to be displayed.

POSITION COUNTERS.

. A chain of markers (underlines of symbol positions) indicate the number of symbol positions left in a line. Initially, the markers extend from the left to right edge in the uppermost line of the crt raster. In this case, the marker in the upper

left corner is called the entry marker. Once a symbol enters that position, the marker is erased and the next marker to the right becomes the entry marker. The entry marker is a Iways the marker closest to the left edge of the raster. When the end of a line is reached, display begins at the left edge of the next lower line (after a horizontal retrace period). The horizontal (X) position counter records the current position in the line as the electron beam moves across the page. At the end